The invention pertains to a device for cutting gear teeth in workpiece wheels by hob peeling with a rotatably drivable workpiece spindle, which holds the workpiece wheel into which the gear teeth, especially internal teeth, are to be cut, and with a rotatably drivable tool spindle, which carries a peeling wheel comprising cutting teeth.
The invention also pertains to a method for cutting teeth in workpiece wheels by hob peeling, in which a workpiece spindle, which holds a workpiece wheel into which the teeth are to be cut, is driven in rotation; in which a tool spindle, which carries a peeling wheel comprising cutting teeth, is driven in rotation in a fixed rotational speed ratio to the workpiece spindle; and in which the peeling wheel is fed forward in the axial direction of the workpiece wheel by means of relative movement between the tool spindle and the workpiece spindle.
The invention also pertains to a peeling wheel with a plurality of cutting teeth arranged in a gear tooth-like manner around a rotational axis.
A device, a method, and a peeling wheel of the type described above are described in DE 10 2007 015 357 A1. The workpiece wheel is rotated continuously by a workpiece spindle. So that the workpiece can be fed forward, the workpiece spindle can be shifted in the direction of its axis. The peeling wheel, which is a tool in the shape of a gear wheel, is rotated by a tool spindle in synchrony with the workpiece wheel. The axis of the tool spindle crosses the axis of the workpiece spindle at a fixed angle; although fixed, this angle can also be adjusted on the machine. During the forward feed, which proceeds continuously as the axes of the workpiece and of the tool are rotated continuously, material is peeled off the blank by cutting edges, which extend along the wide-side contour line of the cutting teeth.
To cut a gear, many strokes can be performed in succession, wherein the cutting depth is increased from cut to cut. The peeling wheel has a regular tooth pitch. A cutting tooth, which comprises cutting edges, is located at each tooth pitch position. All of the teeth have the same shape, so that each tooth of the peeling wheel is always next to identically shaped teeth.
The non-prior art document DE 10 2008 037 514 describes a device and a method for generating internal gearing on tubular tools. In the case of internal gearing, the problem is that the gear teeth of the two meshing sets of teeth overlap each other to a considerable extent. To reduce the extent of the overlapping area, the peeling wheel must comprise a small diameter. This has the result that the overall cutting efficiency is reduced. It therefore becomes necessary to increase the rotational speed. In the case of workpieces with internal teeth of considerable axial length, furthermore, the crossing angle of the axes must be small. This, too, leads to a decrease in cutting efficiency in comparison to the cutting of external gearing.